David Cameron spoke directly to Xi Jinping about the barring of the journalist Robert Hutton. Photograph: Xinhua/Reuters

David Cameron was forced on Monday to protest directly to the Chinese president, Xi Jinping, after a British journalist was barred from attending a press conference in Beijing with the country's premier.

In a sign of the challenge of trying to secure closer ties with Beijing, the prime minister was forced to interrupt discussions with Xi to express unease that the Bloomberg journalist Robert Hutton had been excluded from a press conference with Cameron and his Chinese counterpart, Li Keqiang.

The prime minister raised the matter with Xi as he left a dinner with the president at the State Guest House in Beijing, after Downing Street had spoken out against the "completely inappropriate" decision to bar a journalist from such a high profile event.

The decision by Beijing marred the first day of the prime minister's trip, which is meant to open a "new page" in Britain's relations with the EU. Downing Street will announce on Tuesday that a total of £5.6bn in deals will be signed during the prime minister's three-day visit to China. The most important agreement – a £4.5bn deal involving 100,000 Jaguar Land Rover cars – has been in the pipeline for some time.

But the trade narrative was also diverted as the prime minister acknowledged that he would struggle to meet his pre-election target of lowering net migration to the "tens of thousands", as the latest figures demonstrated an increase in net migration – from 167,000 to 182,000. The prime minister insisted that he is taking tough action to deal with immigration.

Cameron said in January 2010, a few months before the general election, that he aimed to bring net migration down to "the tens of thousands rather than the hundreds of thousands".

However, the latest figures show an increase because fewer Britons are moving abroad. Asked whether he would fail to meet his target, the prime minister said: "I don't accept that. If you take the whole three-year period, net immigration is down by around third."

He said: "The action we have taken takes some time to come through: getting rid of bogus colleges, trying to make sure that people who don't have a right to stay here leave, making sure that family reunion really is just that. A lot of these things take an amount of time to be dealt with." He added that he would "keep going on this".

The ban on the Bloomberg journalist comes at a time when the financial news service is blocked in China, as a result of stories it ran on the wealth of families of senior leaders, including relatives of the president.

Bloomberg last month denied killing a similarly sensitive story following a New York Times report that said editors had been concerned that its ability to report from China would be compromised if it ran the piece.

Bloomberg said the piece was still in preparation.

Hutton was told by an official on a bus ride from Beijing airport, after the prime minister's overnight flight from London, that the Chinese had decided his presence at the press conference a few hours later would not be appropriate.

The official said: "We have been told by the Chinese authorities that it would not be appropriate for you to attend."

A Number 10 spokesman said: "As soon as this issue became apparent on Sunday, we raised our concerns at senior levels and made clear it would be completely inappropriate to exclude journalists from the press statements.

"When we heard what had happened today we expressed our deep concern to senior Chinese officials about journalists being blocked."

But Xi said he knew nothing about the subject when the prime minister raised the matter.

Britain's decision to criticise the Chinese leadership in public on the highly sensitive issue in China of free speech showed that Number 10 is prepared to set boundaries as it opens what Cameron has described as the "next page" in Britain's relations with China.

However, Beijing's refusal to act on British concerns over the press event, where questions were not even permitted, showed that China would also like to highlight some of its red lines in its new relationship with Britain.

Cameron, who was criticised after his stepfather-in-law, Viscount Astor, was invited to join the business delegation, may face further criticism after Healthcare UK signed a memorandum of understanding with CITIC Trust and Circle Partnership, which has close links to the Conservatives.

On the first full day of his visit the prime minister went out of his way to woo Beijing by quoting the father of modern China, Deng Xiaoping. The prime minister opened the day by quoting the famous saying of Deng Xiaoping, who broke with Maoism in the early 1980s to lay the ground for the modernisation of China by likening reform to "crossing the river by feeling the stones".

Cameron said: "The Chinese often talk about crossing the river by feeling your way across stones. It's time to dive together into the deep water and take this partnership the next level. Our destiny lies not in our stars but in ourselves."

Meanwhile, Brussels dismissed as "premature" the prime minister's call for an EU-China free-trade agreement. It is his central proposal of the trip, designed to show how Britain will act as China's strongest advocate in the west, as Number 10 seeks to move on from a row after the prime minister met the Dalai Lama last year.

"We believe that it's premature to discuss a free-trade agreement with China," a spokesman for the EU, Alexandre Polack, was quoted by Bloomberg as telling reporters in Brussels.

At the press conference, Li said China would like to be involved more deeply in Britain's first high-speed rail line north of London and have an increased role in civil nuclear power.

As Cameron said the scale and pace of China's transformation dwarfed Britain's industrial revolution, Li said Beijing would like to invest in power projects.

Speaking in the Great Hall of the People, Li said: "The two sides have agreed to push for breakthroughs and progress in the cooperation between our enterprises on nuclear power and high speed rail. The Chinese side is willing to not only participate in but also purchase equities and stocks in UK power projects. Just like the high speed train, we need to grow this relationship at a higher speed."